Xeloda is a drug taken by mouth that is used as part of a chemotherapy regimen for certain cancers. It is a type of drug called an anti-metabolite. When taken, the body changes it to a compound called 5-fluorouracil (5-FU) which interferes with the division and growth of cancer cells. In some patients with colon, rectum or breast cancer, 5-FU stops cancer cells from growing and decreases the size of the tumor.